Applications and opportunities for ultrasound assisted extraction
in the food industry—A review
Kamaljit Vilkhu a,⁎,Raymond Mawson a,Lloyd Simons a,Darren Bates b
a Ultrasonics Processing Group,Food Science Australia,671Sneydes Road,Werribee,VIC3030,Australia
b Innovative Ultrasonics Pty Ltd,P.O.Box321,Noosaville,QLD4566,Australia
Abstract聂赫留朵夫
Ultrasound assisted extraction(UAE)process enhancement for food and allied industries are reported in this review.This includes herbal,oil, protein and bioactives from plant and animal polyphenolics,anthocyanins,aromatic compounds,polysaccharides and functional compounds)with incread yield of extracted components,incread rate of extraction,achieving reduction in extraction time and higher processing throughput.Ultrasound can enhance existing extraction process and enable new commercial extraction opportunities and process. New UAE processing approaches have been propod,including,(a)the potential for modification of plant cell mat
erial to provide improved bioavailability of micro-nutrients while retaining the natural-like quality,(b)simultaneous extraction and encapsulation,(c)quenching of the radical sonochemistry especially in aqueous systems to avoid degradation of bioactives and(d)potential u of the radical sonochemistry to achieve targeted hydroxylation of polyphenolics and carotenoids to increa bioactivity.
Keywords:Ultrasound assisted extraction;Cavitation;Particle size;Mass transfer
Industrial relevance:The application of ultrasonic assisted extraction(UAE)in food processing technology is of interest for enhancing extraction of components from plant and animal materials.This review shows that UAE technology can potentially enhance extraction of components such as polyphenolics,anthocyanins, aromatic compounds,polysaccharides,oils and functional compounds when ud as a pre-treatment step in a unit process.The higher yield obtained in the UAE process are of major interest from an industrial point of view,since the technology is an“add on”step to the existing process with minimum alteration,application in aqueous extraction where organic solvents can be replaced with generally recognid as safe(GRAS)solvents,reduction in solvent usage,and shortening the extraction time.The u of ultrasonic for extraction purpos in high-cost raw materials is an economical alternative to traditional extraction process,which is an in
dustry demand for a sustainable development.
1.Introduction
The application of ultrasound as a laboratory bad tech-nique for assisting extraction from plant material is widely published.Several reviews have been published in the past to extract plant origin metabolites(Knorr,2003),flavonoids from foods using a range of solvents(Zhang,Xu,&Shi,2003)and bioactives from herbs Vinatoru(2001).A limited number of publications have included continuous ultrasonic process deve-lopment and pilot-scale applications.The range of published extraction applications include herbal,oil,protein and bioac-tives from plant flavones,polyphenolics),sum-marid in Table1and outlined in more detail in the following Applications ction.Much of the work is empirical in nature and explanations of the mechanisms have been propod.Some workers also discuss both the mechanisms involved in UAE and the likely issues for potential for scale up.The review by Vinatoru (2001)outlines a program of work where industrial scale up was attempted under an EU Copernicus grant(ERB-CIPA-CT94-0227-1995).They highlight that while it is relatively easy to achieve extraction on the laboratory bench it is very challenging to attempt extraction on an industrial scale.Several key issues and ob-rvations relating to UAE have been identified,as follows,(1)the nature of the tissue being extracted
and the location of the公司简介文案
⁎Corresponding author.Tel.:+61397313449;fax:+61397313250. E-mail address:kamaljit.vilkhu@csiro.au(K.Vilkhu).
components to be extracted with respect to tissue structures,(2)pre-treatment of the tissue prior to extraction,(3)the nature of the component being extracted,(4)the effects of ultrasonics primarily involve superficial tissue disruption,(5)increasing surface mass transfer(Balachandran,Kentish,Mawson,&Ashokkumar,2006; Jian-Bing,Xiang-hong,Mei-qiang,&Zhi-chao,2006),(6)intra-particle diffusion,(7)loading of the extraction chamber with substrate,(8)incread yield of extracted components and (9)incread rate of extraction,particularly early in the extraction cycle enabling major reduction in extraction time and higher pro-cessing throughput(Moulton&Wang,1982;Caili,Haijun, Quanhong,Tongyi,&Wenjuan,2006).
Living tissues where the desired components are localized in surface glands can be stimulated to relea the components by relatively mild ultrasonic stressing(Toma,Vinatoru,Paniwnyk,& Mason,2001).In tissues where the desired components are located within cells,pre-ultrasound treatment by size reduction to maximi surface area is critical for achieving rapid and complete extr
action (Riera,Golás,Blanco,Gallego,Blasco,&Mulet,2004;Balachan-dran et al.,2006;Vinatoru,2001).Where pre-hydration is necessary to achieve extraction,ultrasound effectively accelerates the hydra-tion process(Vinatoru,2001).Ultrasound induced cavitation bub-bles prent hydrophobic surfaces within the extraction liquid (Grier,personnel communication)thereby increasing the net hydrophobic character of the extraction medium.Thus it is possible to extract polar components into otherwi hydrophilic aqueous extraction media,reducing the need for generally undesirable hydrophobic or strongly polar extraction media.The disruption of tissue surface structures is revealed with microscopic examination by Vinatoru(2001),Chemat,Lagha,AitAmar,Bartels,and Chemat (2004),Haizhou,Pordesimo,and Weiss(2004),Balachandran et al. (2006).Several of the authors in the work cited below highlight concerns due to the potential for ultrasonic cavitation to propagate free radicals,in particular hydroxyl radicals.Where the potential oxidative damage is a concern radical production can be quenched by the addition of small amounts of ethanol to lower the temperatures within the cavitation bubbles and extinguish the chemistry involved(Sun et al.unpublished work in progress).
This paper provides a compilation of food-related UAE applications,highlighting the application approaches and per-formance.Following this,a more detailed discussion is given on UAE mechanisms,process development,equipment design and future opportunities.
2.Applications
2.1.Herbal and oil extraction
Ultrasound has been recognid for potential industrial ap-plication in the phyto-pharmaceutical extraction industry for a wide range of herbal extracts.Vinatoru(2001)published an overview of the UAE of bioactive principles from herbs.The improvement in extractive value by UAE compared with classic methods in water and ethanol for fennel,hops,marigold and mint was34%,18%,2%,and3%respectively in water, whereas34%,12%,3%,and7%,respectively in ethanol.In another study,an aqueous extraction of Geniposide from Gardenia fruit was investigated by Jian-Bing et al.(2006). When ultrasound was applied at0.15W cm−2the extraction yield of Geniposide was incread by16.5%,in comparison with a static process using40ml/g of the solvent volume to fruit weight.The variability in percentage extract yield was mainly due to the individual product structure.Large scale ultrasonic extraction designs were propod for stirred tank systems with temperature control.
In recent years,Albu,Joyce,Paniwnyk,Lorimer,and Mason (2004)investigated the effect of different solvents and ultra-sound on the extraction of carnosic acid from romary.Using conventional stirred 觍颜
extraction ethanol was significantly less effective then ethyl acetate and butanone.The application of ultrasound improved the relative performance of ethanol such that it was comparable to butanone and ethyl acetate alone.
Table1
List of ultrasound assisted extraction studies from the literature on various food components
Product Ultrasound Process Solvent Performance Author
Almond oils Batch,20kHz Supercritical carbon
dioxide 30%incread yield or extraction
time reduction
Riera et al.(2004)
Herbal extracts(fennel,hops, marigold,mint)Stirred batch,
20to2400kHz
黄山宏村Water and ethanol Up to34%incread yield over stirred Vinatoru(2001)
Ginng saponins Batch,38.5kHz Water,methanol
and n-butanol
3-fold increa of extraction rate Wu et al.(2001)
Ginger Batch,20kHz Supercritical carbon
dioxide 30%incread yield or extraction
time reduction
Balachandran et al.(2006)
Soy protein Continuous,20kHz,
3W per gram Water and alkali
(sodium hydroxide)
53%and23%yield increa over
equivalent ultrasonic batch conditions
Moulton and Wang(1982)
Soy isoflavones Batch,24kHz Water and solvent Up to15%increa in extraction efficiency Rostagno et al.(2003) Rutin from Chine Scholar Trees Batch,20kHz Water and methanol Up to20%increa in30min Paniwynk et al.(2001)
Carnosic acid from romary Batch,20and
40kHz Butanone and ethyl
acetate
Reduction in extraction time Albu et al.(2004)
Polyphenols,amino acid and
小孩子反复发烧caffeine from green tea
Batch,40kHz Water Incread yield at65°C,compared with85°C Xia et al.(2006)
Pyrethrines from flowers Batch,20and
40kHz Hexane Incread yield at40°C,compared with66°C Romdhane and Gourdan
(2002)
Thereby ultra-sonication may reduce the dependence on a sol-vent and enable u of alternative solvents which may provide more attractive(a)economics,(b)environmental and(c)health and safety benefits.
Ginnosides(tri-terpene saponins)are known as the prin-cipal ingredients of ginng roots.Ginng saponins are asso-ciated with traditional herbal medicine and health foods(Tang &Einbrand,1992).UAE of ginng saponins was approx-imately3-times faster than the traditional extraction method involving reflux of boiling solvents in a soxhlet extractor. Furthermore,the UAE technique was achieved at lower tempe-ratures which are more favourable for thermally unstable com-pounds(Wu,Lin,&Chau,2001).Similar results were reported on UAE of carvone and Limonene from caraway eds,which resulted in2fold increas in their contents(Chemat et al., 2004).
Likewi,anthraquinones from roots of Morinda citrifolia (Noni)are the active compounds which show veral therapeutic effects and ud in anti-cancer medical applications.Recently, Hemwimol,Pavasant,and Shotipruk(2006)investigated the u of UAE to improve the solvent extraction efficiency of an-thraquinones from the roots of M.citrifolia.Ultrasound extraction in an ethanol water system provided a75%reduction in extraction time and yield comparable with non-sonicated sample.
Supercritical fluid extraction(SFE)is an intrinsically capital intensive process where any enhancement of extraction efficien-cy either in terms of extraction rate or yield is economically attractive.Over a period of many years it has been shown that combined action of ultrasound and supercritical carbon dioxide on extraction could be ud to significantly improve extraction rate or yield of amaranth oil from eds(Bruni,Guerrini,Scalia, Romagnoli,&Sacchetti,2002),almond oil(Riera et al.,2004), tea ed oil(Rajaei,Barzegar,&Yamini,2005),gingerols from ginger(Balachandran et al.,2006),operating parameters such as temperature,pressure and CO2flow for Adlay ed(Coix lachrymal-jobi L.var.Adlay)oil and coixenolide from adlay ed(Ai-jun,Shuna,Hanhua,Tai-qiu,&Guohua,2006).
UAE has been recognid for application in the edible oil industry to improve efficiency and reduce extraction time(Babaei, Jabbari,&Yamini,2006).This potential was bad on UAE increas in oil fro
m soybeans;carvone and limonene from cara-way eds.The ultrasonically induced cavitation was shown to increa the permeability of the plant tissues.Microfractures and disruption of cell walls in soybean flakes(Haizhou et al.,2004)and caraway eds cell wall(Chemat et al.,2004)provided more evidence for the mechanical effects of ultrasound thus facilitating the relea of their contents,in contrast to conventional maceration or extraction.The effects were identified under scanning electron microscopy.Importance was given to the effect of solvent vapour pressure and surface tension on cavitation intensity.
The benefit of using ultrasonic pre-treatment before extract-ing oil from the eds of Jatropha curcas L.,and almond and apricot eds by aqueous enzymatic oil extraction(AEOE) process was evaluated by Shah,Sharma,and Gupta(2005), Sharma and Gupta(2006).Ultrasonic pre-treatment of the almond and apricot eds before aqueous oil extraction and aqueous enzymatic oil extraction provided significantly higher yield with reduction in extraction time.Thus,implementation of ultrasonic pre-treatment reduced oil extraction time that may improve through put in commercial oil production process.
爱是这辈子的坟2.2.Protein extraction
A small pilot-scale ultrasound batch and continuous soy protein extraction trials were reported by Moulton and Wang (1982).The continuous high-intensity application extracted 54%and23%more protein for aqueous and alkali extraction respectively,compared with the batch extraction using com-parable processing times and volumes.During the trials it was estimated that the continuous process ud70%less energy than the batch system to extract the same amount of protein and sonication efficiency improved with the greater load of thicker slurry,up to1:10(flake to solvent)ratio.
2.3.Bioactive extraction from plant materials
2.3.1.Polyphenols
Grape marc is the solid waste of the wine-making process. Consisting of skins,eds,and small amount of leaves,grape marc has long been ud for alcohol,tartaric acid and more recently,the recovery of phenolic compound.Phenolic com-pounds are of particular interest in wine industry as it gives the characteristics colour and flavour in wine,and in pharmaceutical industry for its benefits on human health(Brenna,Buratti,Cosio, &Mannino,1998).Polyphenols are associated with reduced risk of cardiovascular dia by inhibiting in-vitro oxidation of low-density lipoproteins posss anti-ulcer,anti-mutagenic,anti-inflammatory activity and anti-carcinogenic properties(Flamini, 2003;Negro,
Tommasi,&Miceli,2003;Bonilla,Mayen, Merida,&Medina,1998;Palma&Taylor,1999).Phenolic compounds include tannins and colour pigments,anthocyanins which prent at a higher level in red grape marc compared with white grape marc and are more likely to be found on the grape eds(Springett,2001;Palma&Taylor,1999).
The application of ultrasound at Food Science Australia has focud on the u of high-powered systems for extraction of bioactives.Principle targets have been polyphenols and caro-tenoids and in both aqueous and solvent extraction systems.The ultrasound extraction trials have demonstrated improvements in extraction yield ranging from6to35%,as summarid in Table2.Results of ultrasonically treated Shiraz and Sangiove grape marc showed17and35%increa in phenolic com-pounds respectively,However extraction of the compounds yielded much higher recovery from their respective eds (Vilkhu,Food Science Australia unpublished data).
Supercritical carbon dioxide extraction is propod as a better method than ultrasound assisted extraction of polyphe-nolic compounds from grape eds Palma and Taylor(1999).It was believed that the lower catechin(ud as a measure of phenolic content)recovery from ultrasound method could be due to the insufficient power of the solvent ud(aqueous methanol)or due to the degradation of samples during extraction process.Their study was focud on the efficiency of super
critical fluid extraction (SFE)rather than other methods ud in the experiment.The
results of catechin recovery using different extraction methods compared to a control(solvent extraction only)was not available, therefore it was not possible to determine whether ultrasound treatment(although having a lower recovery compared to SFE method)contributed to the increa in catechin recovery relative to a control.Most importantly though,the frequency of ultrasound and other extraction perature)was not stated, therefore it was not known whether suitable frequencies or application conditions were ud.
In recent years it has been shown that pressurized hot water extraction methods offered higher phenolic compound recovery when compared to UAE,hydro-distillation and maceration with 70%ethanol(Ollanketo,Peltoketo,Hartonen,Hiltunen,& Riekkola,2002).The u of methanol during UAE produced the lowest recovery with results not statistically different from maceration with70%ethanol.Potential exists for combining ultrasound as an adjunct with the other extraction procedures to improve efficiency and yield.More recently,Tedjo,Eshtiaghi, and Knorr(2002)studied the quality attributes of grape juices for wine-making using non-thermal process including ultrasound.The non-thermal process examined offered a suitable gentle-action alternative to other cell breakdown methods with incread grape juice yields.Quality analys (e.g.sugar,anthocyanins
and mineral concentration,acidity, colour)showed that non-thermally procesd juices had superior quality to untreated samples and comparable quality to that of enzyme treated grape juices.Likewi significantly enhanced contents of tea polyphenols,amino acid and caffeine in tea infu-sions were recovered with ultrasound assisted extraction when compared with conventional extraction.The nsory quality of tea infusion with ultrasound assisted extraction was better than that of tea infusion with conventional extraction(Xia,Shi,&Wan,2006).
2.3.2.Anthocyanins
Anthocyanins are enjoying greater prominence due to in-creasing public concern with the u of synthetic colouring agents.Anthocyanins reprent a large group of water-soluble plant pigments bad on the2-phenylbenzophyrylium(flavy-lium)structure and there are more than200compounds in this category(IPCS,2001).Anthocyanins are the main colour pig-ments in wild fruits and berries,and predominantly found in the sap of mature cells in grape skin(Springett,2001).The pigments prent in grape skin consist of di-glucosides,mono-glucoside, acylated monoglucosides and acylated di-glucosides of peoni-din,malvidin,cyanidin,petunidin and delphinidin.Anthocya-nins content in grapes varies from30–750mg/100g(Birdle& Timberlake,1997).The wide variation in amount of the compounds is greatly dependent upon cultivar,ason,growing conditions,degree of ripeness,storag
e conditions as well as extraction procedures(Cacace&Mazza,2003).UAE of crushed Shiraz and Merlot grapes by Food Science Australia showed15–18%increa in total colour in grape juice(unpublished data).
A study has been conducted on the potential to u microwave and ultrasound treatments for the extraction of pig-ments from strawberries.Optimal extraction was achieved using microwaves at624W,with a treatment time of60s,together with ultrasonic processing for40s and a ratio of material and extraction solvent of1:6.The stability of the pigment extracts was considerably affected by pH,and achieving a maximum at pH5.0.Addition of sucro or heating at temperatures up to 80°C had little effect on pigment stability.However,pigment stability and colour were greatly improved by addition of citric acid(Cai,Liu,Li,&An,2003).
2.3.3.Tartaric acid
Tartaric acid occurs naturally in fruits,and found in high concentrations in grapes and tamarind(Springett,2001). Approximately90%of the total organic acids in grapes are tartaric and malic acids.Tartaric acid is a by-product in the wine industry since a tremendous amount of tartaric acid from lees has to be removed from the wine after yeast fermentation.Tartaric acid is widely ud i
n bakery operations,wine production,pharma-ceutical industry,hardening of gypsum,confectionery processing and in the chemical industry.Palma and Barroso(2002)optimized the UAE conditions for the recovery of tartaric and malic acid from red and white variety grapes for quantitative determination in wine-making by-products.Our studies on UAE of tartaric esters from red grape marc yielded an increa16to23%from two different varieties(Vilkhu,unpublished).
2.3.4.Aroma compounds
Over a period of many years it has been shown that ultra-sound could be ud to extract aromatic chemicals,which impart bouquet to the wines(Cocito,Gaetano,&Delfini,1995).Solvent mixtures of n-pentane and diethyl-ether(1:2)and dichloromethane were ud to study the optimization of the sonication extraction process.This study emphasid that UAE improved extraction efficiency with incread reproducibility of most aroma com-pounds compared to conventional extraction(Vila,Mira,Lucena, &Fernandez,1999).
An evaluation of UAE of isoflavones from ground soybeans was undertaken by Rostagno,Palma,and Barroso(2003),the efficiency of the extraction was improved by15%but this was dependent on the organic solvent ud.Notably40–60%water
煤化工技术Table2
Examples of bioactive ultrasound assisted extraction work completed at Food Science Australia
Extract target Product Solvent Process Processing conditions Improvement range(%) Beta-carotene Carrot Aqueous Laboratory;24kHz,20–7W s ml−1Ambient15–25
Ethyl-acetate Laboratory;24kHz,20–75W s m−1Ambient8–20
Polyphenols Red grape marc Aqueous Laboratory;24kHz,20–75W s ml−1Ambient11–35
Polyphenols Black tea Aqueous Laboratory;24kHz,8–10W s ml−1Hot processing90°C6–18
Polyphenols Apple Aqueous Laboratory;40kHz,20–75W s ml−1Hot processing80°C6
Gingerol Ginger Supercritical carbon dioxide Laboratory;20kHz Pressure160bar30
was required to improve the extraction efficiency,which was thought to be due to the relative polarity of the isoflavones and incread ultrasound propagation in aqueous systems.Some aromatic compounds such as rutin from the flower buds of Chine Scholar Tree(Sophora japonica)have impr
oved consi-derably with higher levels of organic solvent compared to aqueous conditions.The difference in performance was attributed to hydroxyl radical and hydrogen peroxide formation in aqueous conditions resulting in degradation of the rutin.The application of ultrasound in methanol was considered more effective due to the higher solubility of rutin in methanol and hydrogen peroxide is not formed by ultrasound in methanol (Paniwynk,Beaufoy,Lorimer,&Mason,2001).
In order to extract phycocyanin from Spirulina platensis (Arthrospira platensis)cells,lection of ultrasonic frequency was important(Furuki et al.,2003).The purity of phycocyanin in its crude extract was dependant on ultrasonic frequency.For example,phycocyanin was extracted with higher purity at28kHz than at20kHz,due to the lective extraction of the active component at the frequencies.It was suggested that rapid and lective extraction of phycocyanin from S.platensis may be possible if an optimized ultrasonic application is developed.
2.3.5.Polysaccharides and functional compounds
The extraction of carbohydrates,polysaccharides and other functional compounds has been studied in the recent years. Various extraction procedures with and without a short applica-tion of ultrasound at the beginning of the extraction were ud to examine the effect of sonication on the extractability
of the hemicellulo components of buckwheat hulls(Hromadkova& Ebringerova,2003),cellulo from sugarcane bagas(Sun, Sun,Zhao,&Sun,2004),and xyloglucan from apple pomace (Caili et al.,2006).UAE of the compounds not only acce-lerates the extraction process but also prerves structural and molecular properties.In sugar cane bagas hemicellulo extraction process,UAE improved extractability of hemi-cellulos apparently by destruction of cell walls and cleavage of links between lignin and the hemicellulos(Jing,RunCang, Xiao,&YinQuan,2004).Whereas ultrasonic aqueous extrac-tion of polysaccharides from edible fungus,Pleurotus tuberregium,resulted in the formation of glycan–chitin com-plexes with higher average molecular weight than compounds obtained by hot water extraction(Mei,Lina,Chi-Keung-Cheung,&Eng-Choon-Ooi,2004),which could be due to the sonochemical modification of two polysaccharides.Further improvement in immunological as well as anti-tumour activi-ties of the complexes were reported on animal trials.
UAE can enable extraction at lower temperatures,Xu,Zhang, and Hu(2000)have compared UAE with hot water extraction of flavonoids from bamboo leaves.The laboratory scale trials results showed that the optimal conditions for extraction were achieved using UAE at lower temperature,rather than using hot water bath extraction at80°C.More recently,Rosângela et al. (2007)investigated the chemical composition of Mate tea extracts(leaves of Ilex paraguariensis,a native tree from Brazil).Th
e effect of the ultrasonic treatment resulted in improved mass yield of caffeine and palmitic acid in methanol solvent.Ultrasound enhanced both the kinetics and yield which was attributed to increa in the internal diffusion that controls the transfer of solute to the solvent and also the destruction of pores in which the solute can be trapped.However the efficiency of the extraction will be dependent on the concentration of the methanol solvent employed Rostagno et al.(2003).
2.4.Bioactive extraction from animal materials
There is limited number of publications on UAE from animal material.Attempts were made to extract chitin from fresh water prawn shells(Kjartansson,Zivanovic,Kristbergsson,&Weiss, 2006)and lutein from egg yolk(Xiaohua,Zhimin,Witoon,& Joan,2006)by using sonication.In chitin studies from prawn shells,it was found that the chitin yield decread during soni-cation,this loss was attributed to depolymerization of extracted chitin in the wash water.Subquently,the degree of acetylation of chitins was unaffected by sonication,but the degree of acetylation of chitosans produced from sonicated chitin decread.
Egg yolk is one of the major lutein sources in our foods (Johnson,2004).Lutein in egg yolk is highly bio-available, compared with other sources.It was reported that egg yolk intake significantly increa
d plasma lutein(Handelman, Nightingale,Lichtenstein,Schaefer,&Blumberg,1999). Recently,Xiaohua,et al.(2006)have reported higher extraction yield of luetin when ultrasonic ud in combination of sapo-nificated organic solvent.Further to their report,compared with the traditional saponification solvent extraction method,the UAE extraction method was more effective in extracting lutein from the sample matrix,presumably by avoiding degradation reactions.
3.Extraction mechanisms and process development
Extraction enhancement by ultrasound has been attributed to the propagation of ultrasound pressure waves,and resulting cavitation phenomena.High shear forces cau incread mass transfer of extractants(Jian-Bing et al.,2006).The implosion of cavitation bubbles generates macro-turbulence,high-velocity inter-particle collisions and perturbation in micro-porous particles of the biomass which accelerates the eddy diffusion and internal diffusion.Moreover,the cavitation near the liquid–solid interface nds a fast moving stream of liquid through the cavity at the surface.Cavitation on the product surface caus impingement by micro-jets that result in surface peeling, erosion and particle breakdown.This effect provides exposure of new surfaces further increasing mass transfer.
This phenomenon was confirmed by performed scanning electron micrography on peppermint plant l
eaves and trichomes. After the were ultrasonically treated for menthol extraction, microscopy results indicated that there were two mechanisms involved in extraction:(a)the diffusion of product through the cuticle of peppermint glandular trichomes and(b)the exudation of the product from broken and damaged trichomes(Shotipruk, Kaufman,&Wang,2001).脆怎么读
Acceleration in the extraction kinetics and improved extraction yield of pyrethrine from pyrethrum was largely
